Carburetor cold-start and warm-up system

ABSTRACT

A primer and warmup system for float-type carburetors, in which a fuel enrichment passage connects the float chamber with the induction passage on the engine side of the throttle valve and an air passage connects the fuel enrichment passage with the induction passage near the air intake thereof. A valve in the fuel enrichment passage posterior to the air passage controls the fuel-air mixture formed in the passage to vary the fuel-air mixture supplied to the induction passage in accordance with the engine temperature.

United States Patent Robert W. Sutton Grosse Pointe Farms, Mich. 812,733

Apr. 2, 1969 Apr. 27, 1971 The Bendix Corporation inventor Appl. No. Filed Patented Assignee CARBURETOR COLD-START AND WARM-UP SYSTEM 1 Claim, 6 Drawing Figs.

u.s.c1 261/39, 123/187.5, 123/130, 261/71 lnt.C1 F0261 1/10 FieldoiSearch 261/394, 40, 71, (.C.P.), r.1=.v. 123/1875, 187.5 Reg [56] References Cited UNITED STATES PATENTS 942,785 12/1909 Linaweaver (261/C.P.) 1,321,132 11/1919 Skinner (26l/C.P.) 1,699,324 1/1929 Bracke (26l/C.P.) 2,675,792 4/1954 Brown et al 261/39(.4)

Primary ExaminerTim R. Miles Attorneys-Plante, Hartz, Smith & Thompson and William F.

Thornton CA l' it URIE'IOR COLD-START AND WARM-UP SYSTEM In many vehicle engine installations the space between the hood and engine and/or the area in the engine compartment is limited thus requiring optimum use of the available space in order to place the engine components and accessories in suitable operating position. Further, in order to provide a vehicle with a low silhouette in body design, the hood is often placed in close proximity to the engine, thus leaving only a limited amount of vertical space for the carburetor and air cleaner in the space above the engine. Low and compact carburetors with relatively small air horns and throttle bodies have been designed; however, the conventional float-type carburetor contains the essential elements of a throttle, namely the main and idle jet systems in the main body, the throttle in a separate throttle body, and a choke valve in the air horn or air intake, normally positioned above the main body, and adds appreciably to the overall height of the carburetor, thus interfering with the desired compactness of the engine compartment and low carburetor silhouette and with the satisfactory installation of the air filter. It is therefore one of the principal objects of the present invention to provide a downdraft, floattype carburetor which is of compact and low construction and design for satisfactory installation in a limited space, and of low hood silhouette appearance, yet which contains all the standard system so arranged as to give optimum performance under all normal engine and vehicle operating conditions.

Another object of the invention is to provide a float-type carburetor for an internal combustion engine in which the conventional choke valve for cold-starting is eliminated, and the section of the carburetor nonnally containing the choke valve is reduced in height without sacrificing performance,

and in which a printing system utilizing a rich mixture of fuel and air disposed principally in the body of the carburetor is employed in place of the conventional choke valve.

Still another object of the invention is to provide a carburetor enrichment system for cold-starting which can effectively and readily be adjusted to give optimum performance and avoid flooding under varying starting temperature conditions, and which can be incorportated in the body of the carburetor without rearranging or interfering with the operation of the main and idle systems or requiring appreciable enlargement of the main carburetor body.

A further object is to provide a relatively simple and reliable cold-start enrichment system for carburetors of the aforesaid type, which can be operated either manually from the driver's compartment or by automatic means in response to ambient air and engine temperatures, and which can be made readily responsive to starting under various engine temperature conditions to provide quick starting and continuous optimum operation of the engine during the warmup period.

- Additional objects and advantages of the invention will become apparent from the following description and accompanying drawings, wherein:

FIG. I is a top plan view of a carburetor embodying the present invention;

FIG. 2 is a vertical cross-sectional view of the carburetor shown in FIG. 1, the section being taken on line 22 of the latter FIG;

FIG. 3 is a vertical cross-sectional view of the carburetor shown in the preceding FIGS., the section being taken on line 3-3 of FIG. ll;

FIG. 4 is a fragmentary cross-sectional view of the carburetor taken on line 4-4 of FIG. 1; and

FIGS. 5 and 6 are enlarged fragmentary cross-sectional views of a portion of the carburetor cold-start and warmup system, the section being taken on lines 5-5 and 66 of FIG. 3.

Referring more specifically to the drawings, numeral 10 designates a downdraft, float-type carburetor for an internal combustion engine which may be considered as essentially conventional, except for the improvements constituting the present invention, having an air born 12 to which is normally secured an air filter (not shown) and the main body 16, the throttle body 18 witha throttle 20 mounted therein on a shaft 22 joumaled in the sidewalls of the throttle body, and the induction passage 24 extending from the air inlet 26 to the air outlet 28 on the engine side of the throttle. The carburetor is mounted on an intake manifold by bolts extending through flanges at the lower edge of the throttle body, and the outlet 28 of the induction passage communicates directly therewith. The throttle 20 is controlled by the operator through a linkage (not shown) connected to shaft 22.

The main body 16 includes a large venturi 30, small venturi 32, and a fuel bowl 34 having a float chamber 36 therein, with a float 38 for regulating the level of the fuel in the chamber by controlling a fuel inlet valve 40 at the end of the fuel supply line 42. The float chamber is connected to the throat of the small venturi by a main discharge system, indicated generally by numeral 44 and having a well 46 with a perforated tube 48 therein for receiving fuel from the bowl and delivering said fuel to outlet 50 in the small venturi by a passage 52 connected to the upper end of perforated tube 48 and to an annular groove 54 in the small venturi communicating with outlet 50. In the operation of the main-metering system, fuel flows from the float chamber through a metering orifice into tube 48 where it mixes with air to form a fuel-air emulsion which is delivered through passage 52 to outlet 50 in the small venturi. The carburetor shown contains the conventional idle system, and accelerating pump indicated generally by numerals 60 and 62, respectively, and a power enrichment device. The details of these three components will not be described herein since they do not have any direct bearing on the present invention.

The present primer system is best shown in FIGS. 3, through 6, and is designated to deliver a fuel-air mixture to the induction passage on the engine side of the throttle in an amount varying in accordance with engine temperature. Passages 70 and 72 in the carburetor and throttle bodies, through which the mixture is supplied to the induction passage, is connected to discharge opening 74 below the throttle-and to a mixture forming and control mechanism indicated generally by numeral 78 which includes fuel and air supply passages and a control valve 80. The valve is connected to the float chamber 36 by a passage 82 and-port 84, the upper end of passage 82 being connected to a valve mechanism through a restriction 88. The air for the fuel-air mixture is supplied through conduit 90 connected at its upper end to the induction passage near the air inlet by an orifice or port 92 and to the valve mechanism by a passage 94. The restrictions or orifices 88 and 92 can be varied in size to give the proper starting mixture and prevent flooding. Valve mechanism is of the rotary type, as best seen in FIGS. 5 and 6, which in one position connects both the fuel passage 82 and air passage with fuel-air mixture passage 70, through the arcuate opening 81 communicating with a central passage 83, this position being illustrated in FIG. 5. When the rotary valve is moved to its closed position, as illustrated in FIG. 6, the flow of fuel-air mixture to the en gine is completely out off and the engine operates with the normal fuel-air mixture supplied principally by the main and idle fuel systems. Varying the proportion of the arcuate opening 81 disposed aligned with passage 94 controls the intermediate level of communication between passages 94 and 95. The operation of the valve, whether controlled manually or by automatic means, permits a varying amount of fuel-air mixture to enter passage 70, thereby adjusting the richness of the fuelair supply to the engine to satisfy engine requirements under starting and warmup temperature conditions. Since the arcuate opening 81 is of substantially less width than the passages 94 and 95, turbulent flow occurs thereacross from full open through the inten'nediate values to insure good mixing of the fuel-air emulsion. In the embodiment of the invention illustrated in the drawing, the rotary valve 80 is journaled in a bore 95 in the main body and is controlled by a linkage connected to a lever 96 secured to a stem 98 on the outer end of the valve.

In the operation of the carburetor with the present priming system incorporated therein, starting with the engine cold, rotary valve 80 is moved to the position illustrated in FIG. 5,

thus connecting passage 70 with the fuel bowl through passage 90, orifice 88, passage 82 and port 84, and simultaneously connecting passage 70 with the air inlet of the carburetor through passage 90 and port 92. When the engine is being cranked with the throttle valve in a substantially closed position, the vacuum created by the engine is transmitted through passage 70 and simultaneously to fuel passage 82 and air port 92, thereby drawing the fuel and air into valve 80 where the fuel and air are mixed to form an emulsion which flows through passages 70 and 72 to port 74 where it is discharged into the induction passage, thus enriching the mixture over and above that supplied by the main-metering and/or idle jets. As the engine commences to run, the manifold vacuum is still transmitted through passages 72 and 70 to the fuel and air passages 82 and port 90 to continue the supply of enriched mixture to the engine. With the manual type of primer shown in the drawings, the operator gradually closes rotary valve 80 as the engine becomes warmer, thereby diminishing the amount of fuel enrichment to the engine. When the engine has become fully warm, valve 80 is fully closed and remains closed as long as the engine is running under normal operating conditions.

In the present priming system, the enriched fuel mixture which provides the additional richness to the normal mixture supplied to the engine, mixes readily with the air passing through the induction passage and gives quick and effective response to engine requirements, and eliminates the injection of much of the raw fuel into the cylinders, which frequently occurs with the conventional type of choke valve. The present system does not require any substantial increase in size or height of the carburetor body in which the system is incorporated, thereby conveniently permitting a low and compact carburetor design.

While only one embodiment of the present carburetor has been described in detail herein, various changes and modifications may be made without departing from the scope of the invention.

lclaim:

1. In an internal combustion engine carburetor having a fuel bowl, main and idle jet fuel systems, and an induction passage with a throttle therein: a cold-start and warmup system comprising a fluid passage connecting the fuel bowl with the induction passage on the engine side of the throttle, a passage connecting said fluid passage with a source of air to form a fuel-air emulsion in said fluid passage for delivery to the induction passage on the engine side of the throttle, in addition to that supplied by the main and idle systems, a valve in said fluid passage posterior to the connection with said air passage, said valve including a member journaled in said carburetor and including an axially extending central passage defining a portion of said fluid passage posterior to the connection with said air inlet and also including an arcuate opening in said member substantially less in width than said passage with said central passage and means varying the communication between said fluid passage and said central passage by varying the portion of said arcuate opening disposed therebetween; and a means for controlling said valve to vary the flow of fuelair mixture to the engine during the warming-up period thereof. 

1. In an internal combustion engine carburetor having a fuel bowl, main and idle jet fuel systems, and an induction passage with a throttle therein: a cold-start and warmup system comprising a fluid passage connecting the fuel bowl with the induction Passage on the engine side of the throttle, a passage connecting said fluid passage with a source of air to form a fuel-air emulsion in said fluid passage for delivery to the induction passage on the engine side of the throttle, in addition to that supplied by the main and idle systems, a valve in said fluid passage posterior to the connection with said air passage, said valve including a member journaled in said carburetor and including an axially extending central passage defining a portion of said fluid passage posterior to the connection with said air inlet and also including an arcuate opening in said member substantially less in width than said passage with said central passage and means varying the communication between said fluid passage and said central passage by varying the portion of said arcuate opening disposed therebetween; and a means for controlling said valve to vary the flow of fuel-air mixture to the engine during the warming-up period thereof. 